Question
When we moved into our house about 3 years ago it had an existing lawn that was not cared for very well. My husband and I have tried a few things in the past but really did not get any results from it. Now we are pretty serious about trying to fix the problems, but to do it ourselves. We have centipede grass and have no trees in the back yard and one small tree with very very little shade in the front. The back yard seems COOKED! We have not treated it or began watering it yet. However, the front yard has more green grass and a ton of weeds. We fertilized it with weed and feed a couple of days ago and prior to that I had started to water it in the afternoons for about a half an hour at least 5 days of the week. I really do not see an improvement. We live in Mississippi and it gets above 90 degrees here often and we have no shade. The grass near the house that gets a little shade looks pretty good but the rest looks awful. Do I have the wrong grass or is there something I can do to save what I have?

Answer
Centipede is a low maintenance grass for hot climes.  It requires a few maintenance practices to favor healthy growth:
low mowing   .5 to 1.5 inch height, 2" in summer
thatching if needed
water 1 to 2 inches per week
fertilize at low rate after green up in spring, .5 to 1# N/1000 sq. ft.
pH range of 5.0 to 6.5

However, it does have some common diseases which can effect growth:
brown patch, nematodes, centipede mosaic, take all root rot, dollar spot and fairy ring
A plant tissue analysis and soil test from you rlocal ag/hort agent may be necessary to determine the culprit and treatment.
The first four can create large brown patches in the lawn and prevent water uptake or recovery with normal watering and maintenance.

Once the cause is diagnosed, treat with recommended fungicide or nematicide.  Fungicides are best used as preventative in spring.  A lawn renovation (verticutting or thatching) and overseeding should produce a better lawn after treatment takes hold.  If fungal, it may take a season or two for recovery.
Best of luck.